Following are publications which disclose background information closely related to the present invention. These publications are discussed in greater depth in the Background sections indicated. M. W. Bevan et al. (1983) Nature 304:184-187, R. T. Fraley et al. (1983) Proc. Natl. Acad. Sci. USA 80:4803-4807, and L. Herrera-Estrella et al. (1983) Nature 303:209-213, disclosed use of the nos promoter to drive expression in plants of bacterial antibiotic resistance structural genes (see Manipulations of the TIP Plasmids). R. F. Barker et al. (1983) Plant Molec. Biol. 2:335-350, and R. F. Barker and J. D. Kemp, U.S. patent application Ser. No. 553,786 disclose the complete sequence of the T-DNA from the octopinetype plasmid pTi15955; homologous published sequences of other Ti plasmid genes are referenced therein (Genes on the TIP Plasmids). N. Murai and J. D. Kemp (1982) Nucleic Acids Res. 10:1679-1689, disclosed the existance and approximate location of a 1450 base transcript (1450bTx), identified therein as having a size of 1600 bases, encoding open reading frame (ORF) 24 of the sequence. S. B. Gelvin et al. (1981) Plasmid 6:17-29, disclosed that T.sub.R is transcribed in Agrobacterium cells and in plant cells (Genes on the TIP Plasmids). S. J. Karcher et al. (1984) Mol. Gen. Genet., mapped the position of the 1450bTx (Example 1). The dual-purpose functional properties derived from the 1450bTx promoter region (1450bTxPR), as disclosed and taught herein, were not reported in the aforementioned references. L. Herrera-Estrella et al. (1983) EMBO J. 2:987-995, reported that structural genes encoding resistances to kanamycin and methotrexate were expressed in both bacterial and plant cells when placed behind the nos promoter.